CC | Supporting Ventilation/ Respiratory System

Oxygen Therapy & Delivery Systems

• Target: Maintain SpO2 >92% (or >88% in chronic COPD) or PaO2 >60 mmHg. Supplementing FiO2 >60% for >24 hours risks oxygen toxicity, causing severe pulmonary edema and inflammatory alveolar damage.
• Low-Flow Systems: Nasal Cannula (1–6 L/min, 24%-44% FiO2), Simple Mask (6–12 L/min, 35%-50% FiO2, requires >=6 L/min), Non-Rebreather (10–15 L/min, 60%-90% FiO2, keep reservoir bag inflated).
• High-Flow Systems: Venturi Mask (delivers precise, fixed FiO2 for COPD), High-Flow Nasal Cannula (up to 60 L/min, 100% FiO2, heated humidification).
• CO2 Narcosis: Some COPD patients lose sensitivity to high CO2, relying on a hypoxic drive to breathe. However, never withhold oxygen during severe, life-threatening hypoxemia.

II. Artificial Airways & Ventilation Modes

• Airways: NPA (used in conscious or unconscious patients) vs. OPA (strictly unconscious patients to avoid vomiting/aspiration). Verify ET tube placement immediately via bilateral breath sounds, symmetric chest movement, and EtCO2 capnography; confirm via chest X-ray (2–3 cm above carina).
• Cuff Management: Keep cuff pressure at 20–30 cm H2O to prevent aspiration and protect tracheal capillary perfusion.
• Ventilation Modes:
  • AC (Assist-Control): Preset rate/VT. Spontaneous breaths get full VT; risks hyperventilation and respiratory alkalosis.
  • PC (Pressure Control): Preset pressure; VT varies. Prevents barotrauma in "stiff" or noncompliant lungs.
  • SIMV: Preset rate/VT; spontaneous breaths vary in volume.
  • PSV (Pressure Support): Preset pressure assisting spontaneous breaths; patient controls rate/VT to facilitate weaning.
• PEEP: Splints open alveoli. High PEEP risks decreased venous return, preload, and cardiac output due to increased thoracic pressure.

III. Nursing Interventions & Complications

• Suctioning: Only PRN (not routinely). Hyperoxygenate with 100% FiO2 before/after; limit passes to <10 seconds. Stop insertion when meeting resistance (carina) to avoid mucosal damage.
• VAP Prevention: Elevate HOB 30–45 degrees, perform daily SAT/SBT trials, provide oral care with Chlorhexidine, and initiate early mobility.
• Unplanned Extubation: Stay with the patient, call for help, and manually ventilate with BVM and 100% O2.
• Accidental Decannulation (Trach <7 days): Spread stoma with hemostat, insert tube with obturator, then remove obturator; if impossible, cover stoma and use BVM over mouth/nose.

IV. Chest Tubes & Drainage Systems

• Water-Seal Chamber: Shows tidaling (water rises on inspiration, falls on expiration). Cessation means lung re-expansion or tube occlusion. Continuous bubbling indicates an air leak.
• Disconnection: Submerge the distal end in sterile water to re-establish a water seal. Never routinely clamp or strip chest tubes.